Wikipedia Reference Information
Clicks are stops produced with two articulatory closures in the oral cavity. The pocket of air enclosed between the two closures is rarefied by a sucking action of the tongue. The release of the more forward closure produces what in many cases are the loudest consonants in the language, although in some languages such as Hadza, clicks are more subtle and may even be mistaken for ejective stops. Clicks appear more stop-like or more affricate-like depending on their place of articulation: Clicks involving an apical alveolar or laminal postalveolar closure are acoustically abrupt and sharp like plain stops, while bilabial, dental and lateral clicks have a longer and acoustically noisier sounds that are more like affricates.
The complete, up-to-date and editable article about Click Consonant can be found at Wikipedia: Click Consonant